Passenger protection systems, such as, for example, safety belts, today are standard equipment in motor vehicles. The snap connections of the safety belts lock in a belt lock and protect the passengers of an automobile or of another type of vehicle in the event of an accident. The belt locks are generally associated with detection elements, which detect the state and position of the safety clasp of the safety belt in the belt lock. By means of the detection elements, it is determined whether the belt is locked or unlocked, and the passengers are aurally notified and/or the driver is aurally and/or optically notified.
From U.S. Pat. No. 6,079,744, a belt lock with a detection unit for the safety claps of the safety belt is known. The safety clasp is incorporated on a flexible safety belt. By means of the safety claps, the flexible safety belt is engaged and locked in the belt lock. Within the belt lock, a pin made of ferromagnetic material is disposed, which can be moved between inoperative and operative positions, in which the safety clasp of the safety belt is arrested within the belt lock. On the belt block, a magnetic field sensor is incorporated. By means of a magnet, a magnetic field is produced, whereby the magnet is included at a distance to the magnetic field sensor on the belt lock. The magnet and the magnet field sensor form a space, within which the magnetic field detected from the magnetic sensor changes the pin in a non-operational position, an operational position with the safety clasp, and an operational position without the safety clasp.